Revert "Volume: Hide dialog when motion cancelled, as well as when finished."

This reverts commit 3f8dd359.

Reason for revert: b/273157752 (long press flicker)

Bug: 273157752, 232606092

Change-Id: Iafd7dce156fea867d16bb3709700e01a19c043b4
(cherry picked from commit on googleplex-android-review.googlesource.com host: 9bdfa459)
Merged-In: Iafd7dce156fea867d16bb3709700e01a19c043b4